OBJECTIVE:
To describe the new American Heart Association (AHA) guidelines for pediatric
life support, based on the scientific evidence evaluated by the International
Liaison Committee on Resuscitation, and endorsed and disseminated by North American
resuscitation councils.SOURCES: The guidelines for basic and advanced life support published
in Circulation in November 2005 were reviewed together with subsequent
publications on the same topics, identified in PubMed and MEDLINE using the
keywords cardiac arrest, basic life support, advanced life support, cardiopulmonary
resuscitation and pediatric resuscitation.SUMMARY OF THE FINDINGS: The greatest guideline changes are in the area
of basic life support. The new guidelines emphasize the new chest compression/ventilation
ratio for trained health professionals, which is now 15:2 for all children except
neonates. Also emphasized is the need for harder and faster chest compressions,
and the need to avoid hyperventilation during and after cardiorespiratory arrest.
The use of high-dose epinephrine has been removed, as have some other previous
recommendations.CONCLUSIONS: The most recent AHA guidelines for pediatric resuscitation
are focused primarily on basic life support care. They are based on the best
available scientific evidence, although further research is required to validate
these changes and provide new evidence for future guidelines.

With the objectives
of standardizing the care of critically ill children and increasing their likelihood
of survival, the International Liaison Committee on Resuscitation (ILCOR) analyzes
the resuscitation literature, and every 5 years publishes an evidence-based
evaluation of resuscitation science. Many of the world’s resuscitation
councils then translate the evidence into treatment recommendations known as
guidelines. In November 2005 the new American Heart Association (AHA) guidelines
for cardiopulmonary resuscitation (CPR) were published in Circulation,1
and the new training manuals published by the AHA are currently available for
use in training courses for health professionals.2

Adequate basic
CPR, rapid access to emergency medical services, provision of advanced life
support and prevention of secondary sequelae are necessary to achieve good outcomes
in critically ill children. The most significant changes to the pediatric guidelines
have been extrapolated from studies performed on manikins, adult humans or animals.
The objective of this brief review is to point out the changes that were made
in the latest resuscitation guidelines and to relate them to the Brazilian context.

The authors reviewed
the 2005 AHA guidelines for basic and advanced pediatric life support,1
in addition to the many worksheet reviews performed as part of the ILCOR process.
Studies published on these topics since December 2005 were also reviewed, using
the PubMED and MEDLINE databases. The keywords searched were cardiac arrest,
basic life support, advanced life support, cardiopulmonary
resuscitation and pediatric resuscitation.

Airway and
ventilation

The first step
necessary in caring for the critically ill child is the rapid recognition of
respiratory failure, since this is the most common cause of cardiorespiratory
arrest (CRA) in children. Signs such as tachypnea, erratic respiration, nasal
flaring, intercostal retractions, moaning, cyanosis and altered level of consciousness
are important markers of respiratory distress.

Pre-hospital support
of ventilation and oxygenation by means of bag-mask ventilation is safer than
and as effective as tracheal intubation, providing it is performed correctly.3-5
An adequate seal between face and mask is crucial! Opening the airway with mild
extension of the neck is necessary for adequate chest expansion, which is the
best indicator of good ventilation. If chest expansion is insufficient, it is
necessary to reassess the position of the patient, the size of mask and adequacy
of seal between mask and face.

During ventilation
with bag and mask, gastric distention can occur, which can compromise ventilation6
and lead to aspiration of gastric contents. In order to avoid this, care should
be taken to use the lowest inspiratory pressure needed to move the chest. Cricoid
pressure can be applied to minimize the risk of aspiration in the unconscious
patient.3,6 After intubation, a nasogastric or orogastric tube can
be used to reduce intraabdominal pressure.

An important guideline
change: laryngeal masks are as effective as tracheal intubation, but should
only be used by professionals experienced in their use.7

In the past, cuffed
tracheal tubes were only recommended for children over 8 years of age, as the
natural subglottic "narrowing" in young children can function as
a physiological cuff. In the 2005 AHA guidelines, cuffed tracheal tubes can
be used for children of all ages except neonates.8-10 Advantages
to the use of cuffed tracheal tubes include that the cuff offers a certain level
of protection against gastric aspiration, in addition to optimizing ventilation
by minimizing air leakage. This is especially important in situations where
there is poor lung compliance or increased airway resistance. Another relevant
consideration is the reduced number of reintubations necessary to achieve the
appropriate sized endotracheal tube (ETT).8 The following formulas
can be used in choosing ETT size:

- Tracheal
tube with cuff (mm) = (age in years/4) + 3;

- Tracheal
tube without cuff (mm) = (age in years/4) + 4.

There have been
long-standing concerns that the use of cuffed tubes in small children could
damage the tracheal mucosa, increasing the risk of subsequent subglottic stenosis.
Subglottic stenosis is generally associated with the use of excessively sized
endotracheal tubes, and with prolonged duration of intubation. As the size of
cuffed tracheal tube used for a child should be smaller than the chosen size
of uncuffed tube (see the formula above), this risk should be reduced. It is,
however, extremely important that cuff pressure be routinely checked. Pressure
should be kept below 20-25 cm H2O, in order to allow sufficient perfusion
of the tracheal mucosa and to avoid ischemia.8-11 in North America,
the presence of respiratory technicians in intensive care units (ICU) facilitates
rigorous monitoring of ETT cuff pressures. In Brazil, this careful monitoring
may become diluted among the many responsibilities of ICU physicians and nurses,
but must be strived for as the appropriate standard of care to be provided to
critically ill patients.

There is no single
method that is 100% accurate for verifying correct ETT position after tracheal
intubation, despite the common practices of relying on auscultation, the presence
of water vapor in the tracheal tube, and chest expansion. The confirmation of
exhaled CO2 using a colorimetric detector(low cost) or by capnography
to confirm ETT position is simple to apply and reliable in children with a perfusing
rhythm weighing more than 2 kg. The correct ETT position must be verified soon
after intubation and immediately after any movement of the patient.11-14
There is not enough data to recommend for or against the measurement of exhaled
CO2 during a pediatric cardiac arrest.

What is perhaps
the greatest change in the new guidelines relates to hyperventilation! This
should be avoided at all costs during resuscitation.15,16 With hyperventilation,
intrathoracic pressure increases, reducing cardiac output and coronary perfusion.
The reduction in CO2 levels during hyperventilation also reduces
cerebral blood flow and increases the risk of cerebral ischemia. The resulting
respiratory alkalosis leads to a displacement of the oxygen-hemoglobin dissociation
curve to the left and, consequently, reduces the delivery of oxygen to the tissues.
The recommended ventilatory rate during CRA is from 8 to 10 breaths per minute.
If the patient’s airway has been intubated, it is not necessary to stop
chest compressions while providing ventilations. If the patient has only suffered
a respiratory arrest, the ventilated rate should be between 12 and 20 breaths
per minute.3,17

Hyperventilation
is a useful/recommended strategy only when caring for patients with increased
intracranial pressure, and an immediate risk of transtentorial herniation.

Compression/ventilation
ratio

The ideal ratio
for compressions and ventilation for children in cardiac arrest is unknown.
The 2000 AHA guidelines recommended different ratios for different ages: 3:1
in newborn infants, 5:1 for up to 8 years of age, and 15:2 in children over
8 years of age. This was difficult to remember!

In children, CRA
is generally the result of hypoxemia, justifying the choice of a greater ventilation/compression
ratio (more ventilations per cycle). Evidence does exist, however,16-18
for the relatively greater importance of chest compressions:

- in victims
of cardiac arrest secondary to hypoxia, the amount of ventilation required
to maintain the ventilation-perfusion relationship is reduced, as cardiac
output is also reduced during CPR;

- in patients
where arrhythmia is the cause of cardiac arrest, ventilation is relatively
less important than chest compressions;

- there
is a significant reduction in coronary perfusion during the time that chest
compressions are suspended in order to provide ventilation during CRA;

- when
there is only one resuscitator, using a compression: ventilation ratio of
5:1, the time taken to change positions between ventilation and compressions
can occupy up to 30% of the total time spent performing CPR;

- using
the 5:1 compression/ventilation ratio, a higher PO2 is achieved than with
15:2, but, since cardiac output is reduced, there is still less oxygen supplied
to tissues;

- the
number and duration of interruptions in chest compressions relates directly
to a lower chance of restoring a spontaneous circulation.

For health professionals,
the compression/ventilation ratio should be 15:2 for children of all ages (except
neonates). For educational reasons and for the reasons cited above, the decision
was made to recommend for a single chest compression/ventilation ratio for CPR
when provided by lay resuscitators, or single rescuers (generally in a pre-hospital
setting), with a ratio of 30:2 being recommended for adults and children (beyond
the newly born).

The guidelines
emphasize the importance of minimizing interruptions to chest compressions,
and of stressing the quality of compressions - harder and faster - in order
to restore a spontaneous circulation. Once the patient’s airway has been
secured with tracheal intubation or a laryngeal mask, it is no longer necessary
to interrupt chest compressions to provide ventilations; in that setting, compressions
should continue at 100/minute, and ventilations be provided at 8-10 breaths/minute.

Animal studies
have proved that good CPR technique is an important factor in optimizing neurological
outcome. If it is not possible to perform both chest compressions and ventilations,
the simple provision of either is better than no resuscitation efforts at all.19,20

Circulation

Faced with a child
in suspected cardiac arrest, the time taken to check for a pulse must be no
more than 10 seconds. If after this time it is not possible to detect the brachial
pulse (infant) or the femoral pulse (older child) in a child who is not responding
to stimuli (does not move or breathe normally), then chest compressions are
begun. Studies have shown that even health professionals have problems confirming
the presence or absence of a pulse.21,22 If a heart rate of less
than 60 beats per minute is confirmed, coupled with signs of low cardiac output,
chest compressions should be initiated. Compressions should be applied to the
lower half of the sternum for children of all ages, taking care not to compress
over the xiphoid process. After each compression, the chest is allowed to recoil
completely to allow blood to return to the heart.23 In infants and
younger children, the two thumb technique, with the professional’s hands
encircling the patient’s chest, is the favored technique. Greater compressive
force and increased intrathoracic pressure allows for increased coronary perfusion
when compared to the two finger technique.24 For older children,
one or both hands should be placed over the lower sternum using the heel of
the hand, as with adults, in order to achieve sufficient force to adequately
compress the chest, i.e. to 1/3 to 1/2 its diameter. The rescuer needs to avoid
flexion of the elbows, and must keep his arms completely extended. Compressions
should be at a rate of 100/minute, with minimal interruptions. Adequate chest
compressions are essential for the return of spontaneous circulation.25

Sudden cardiac
arrest in children is generally due to ventricular fibrillation, or ventricular
tachycardia (VT) with no pulse. In this situation a defibrillator should be
used as quickly as possible. While awaiting the arrival of a defibrillator,
chest compressions should be provided.25 Automated external defibrillators
can be used for children over 1 year of age.26 They have become commonplace
in public areas such as airplanes and shopping centers. The use of biphasic
defibrillators is at least as effective as monophasic ones, and causes less
myocardial damage. Pediatric pads are used for children less than 10 kg, and
adult sized ones otherwise. The first shock should be 2 J/kg. Three sequential
(‘stacked’) shocks are no longer recommended.

After a single
defibrillation, it is necessary to restart compressions immediately and continue
for 2 minutes before checking for pulse and heart rhythm. If necessary, the
next shock delivered should be 4 J/kg. If the rhythm remains unchanged after
two defibrillations, the use of drugs is indicated. The first choice is epinephrine,
but after that, antiarrhythmic agents such as amiodarone can be used. The new
sequence is now: shock (2 J/kg) → CPR for 2 minutes → check rhythm/pulse
→ shock (4 J/kg) → CPR for 2 minutes + drug - check rhythm/pulse →
shock (4 J/kg) → CPR + drug.

Medications
used during cardiorespiratory resuscitation

The preferred routes
for administration of medication during cardiac arrest are intravenous or intraosseous.
In patients where there is difficulty obtaining intravenous access, an intraosseous
needle should be immediately placed.

The delivery of
medication via ETT is being discouraged. The absorption of drugs given by this
route is inconsistent. Post-resuscitation hypertension can occur as a result
of the slow absorption of intrapulmonary epinephrine.27 Diastolic
hypotension resulting from the β-agonist effect of the epinephrine can
potentially occur as well, causing coronary hypoperfusion.28 Another
important negative feature of giving drugs via the ETT is that chest compressions
must be suspended while the medication is administered. Nevertheless, in patients
with no other vascular access who have already been intubated, the administration
of lipid soluble drugs (atropine, naloxone, epinephrine and lidocaine - ANEL)
via ETT is still an accepted option in the most recent AHA guidelines. Ideal
drug dosages for endotracheal administration are unknown. Animal studies suggest
that larger drug doses are needed, always followed by a 5 mL saline flush, and
five ventilations to improve drug absorption. Drugs administered via ETT should
have dosages adjusted as follows: epinephrine (0.1 mg/kg), atropine (0.03 mg/kg)
and lidocaine (2-3 mg/kg).

The 2005 AHA guidelines
offer some other recommendations on medication use during CPR:

- Epinephrine:
this is the most commonly given drug during cardiac arrest, at a dosage of 0.01
mg/kg (0.1 mL/kg using a drug concentration of 1:10,000). The use of high doses
- 0.1 mg/kg (0.1 mL/kg at a concentration of 1:1,000) - is discouraged, as the
majority of studies do not demonstrate a survival benefit over the standard
dose, and its use is possibly associated with worsened neurological outcomes.29
The exception to this recommendation is in cases of intoxication by β-blockers,
when high dose epinephrine may be necessary.

- Amiodarone:
reduces atrium-ventricular (AV) conduction, prolongs the AV node refractory
period and slows ventricular conduction. It should be given in boluses of 5
mg/kg up to a maximum total dose of 15 mg/kg; slow infusion is recommended (20
to 60 minutes) in order to reduce side effects, such as hypotension, bradycardia
and cardiac conduction blockade. Amiodarone can be used by continuous infusion
at a dosage of 5-15 mcg/kg/min after the bolus dose. Amiodarone is being used
with increased frequency for the treatment of supraventricular arrhythmias,
especially in cardiac ICU for the treatment of junctional tachycardia, VT and
ventricular fibrillation, as it suppresses premature ventricular depolarization.
Unfortunately, the majority of data on this drug’s use has been extrapolated
from adult studies.30

- Glucose:
should not be administered during CPR, except when hypoglycemia is documented.
Hyperglycemia is associated with poor prognosis in CPR.31

- Vasopressin:
this is still a controversial drug in CPR. Some adult studies have demonstrated
that vasopressin has similar efficacy to epinephrine during cardiac arrest.
However, there is only one pediatric study,32 with four patients,
in which it was used as a rescue drug after prolonged cardiac arrest, with spontaneous
circulation returning in three patients. Animal studies have shown that vasopressin
when used with epinephrine, improves outcome.33 The role of vasopressin
in pediatric CPR is still inconclusive, and further studies need to be performed
before it can be definitively recommended.

Rhythm disturbances

For the treatment
of supraventricular tachycardia in the hemodynamically stable patient (palpable
pulse and normal arterial pressure), vagal maneuvers may be used initially (for
example: ice on the face), but, in the event of treatment failure, the drug
of choice is adenosine at a dose of 0.1 mg/kg, or 0.2 mg/kg in cases refractory
to the initial dose. Adenosine has a short half-life and should be injected
rapidly. The most effective means of administration is to use two syringes at
the same time, one containing the drug and the other with a the saline solution
push.

Amiodarone is also
useful in treating pediatric supraventricular tachycardia, and can be used (with
the doses cited above) when adenosine has failed to convert to, or to maintain
a normal sinus rhythm, in hemodynamically stable patients. Procainamide, in
doses of 15 mg/kg by infusion over 30-60 minutes, is another treatment option
if other interventions fail. Significant hypotension and heart block may occur
during the infusion of procainamide, especially if given after amiodarone.

Hemodynamically
unstable patients with supraventricular tachycardia should receive electrical
cardioversion as quickly as possible.34 Remember to set the defibrillator
to synchronized mode! The dose is 0.5-1 J/kg on the first attempt and 2 J/kg
in subsequent attempts.

Hemodynamically
stable patients with VT can be treated with amiodarone or procainamide (at the
doses already cited). In VT patients without a pulse or VF victims, CPR should
be started immediately while awaiting a defibrillator, as defibrillation is
the treatment of choice.

Post-cardiorespiratory
arrest management

As soon as a spontaneous
circulation has returned, the objective of further treatment is to maintain
the patient’s hemodynamics and to minimize possible neurologic sequelae.

Hyperventilation
after CRA is detrimental and should be avoided. Hyperventilation causes reduced
venous return to the heart and subsequent cardiac output, and reduces cerebral
blood flow. Acceptable levels of pCO2 depend on the clinical circumstances.
When caring for patients with asthma or severe lung disease, elevated levels
of pCO2 may be tolerable (permissive hypercapnia), while in neurological patients,
normal levels of pCO2 should be maintained.

Studies of some
adults post-CRA suggest that periods of post-resuscitation moderate hypothermia
(32-34 ºC) offers protection to the central nervous system (CNS) with subsequently
improved neurologic outcome. After CRA, hyperthermia is a common occurrence
and is associated with worse prognosis. In patients who remain comatose after
CPR, the new guide suggests maintaining body temperature between 32 and 34 °C
for 12 to 24 hours.35-37

After CRA there
is significant myocardial dysfunction and attention should be given to maintaining
patient hemodynamics, if necessary with the use of inotropic and vasoactive
drugs.

Hyperglycemia and
hypoglycemia in critically ill children are associated with a lower chance of
survival and worsened neurologic progress. It is unclear whether this is the
cause or merely an association with worsened outcome. In critically ill adults
in surgical ICU, strict glycemic control may lead to improved outcome.31
Later studies aimed at maintaining normal glucose levels in patients in an adult
medical ICU did not demonstrate the same protective effect.32 The
unnecessary administration of glucose during or soon after CPR may impact negatively
on prognosis.31 Therefore, the objective is to maintain normoglycemia.

Post-cardiorespiratory
arrest prognosis

There is unfortunately
no clear indicator suggesting at what point continued efforts of CPR are futile.
There are certain indicators that suggest a likelihood of better prognosis,
including: short duration of CRA, early initiation of CPR, hypothermia as the
cause of CRA (rare in Brazil), CRA in a hospital environment and prompt extracorporeal
circulation after CRA.38,39 Duration of resuscitation is directly
related to neurological prognosis, i.e. the longer CPR lasts the greater the
risk of neurological damage. There are isolated reports of prolonged CRA with
minimal sequelae, in particular when good CPR is performed. For these reasons
there is no consistent guideline as to when to stop resuscitation.40,41

Presence of
the family during cardiopulmonary resuscitation

Recent studies42
analyzed a practice that is in vogue in North America, which is to allow families
to be present during CPR on their loved ones. The reactions of family members
and the attitudes of health professionals have been positive. This practice
is not a recommendation of the new guidelines, merely an observation/option.
Nevertheless, to allow parents or guardians to be present, with the help of
appropriate support (social worker, cleric or nurse) to explain in real time
what is taking place is worthy of consideration by those responsible for local
emergency rooms and ICU.

Conclusions

The goal of resuscitation
guidelines is to improve the care provided to critically ill children. Every
5 years, ILCOR performs reviews of the relevant literature and publishes its
recommendations so that national/regional resuscitation councils can re-align
their protocols, striving for optimal care in cases of CRA. Unfortunately, the
majority of the guidelines changes for pediatrics are extrapolated from studies
with manikins, adult humans and animals. The emphasis on good basic life support
in these latest guidelines, such as the pre-hospital universal compression/ventilation
ratio of 30:2, justifies redoubling the efforts in training society’s
first-responders.

Only time and further
study will reveal whether the outlined changes in the 2005 AHA guidelines will
have a positive impact on the survival of children who are victims of CRA. At
the very least, these are the best guidelines that can be currently made, based
on the little pediatric evidence that exists.